1. Field of the Invention
This invention relates to a vacuum type brake booster for reducing the brake pedal depressing force of automobiles.
2. Description of the Prior Art
Brake boosters generally installed within an engine compartment of vehicle and engine intake manifold are used as a negative pressure source for the booster. Since the volume of the vacuum obtained from the intake manifold is limited to a certain amount, the size of the brake booster itself is required to be larger if a larger amount of output thereof is needed. However, in the space provided the engine there are many other devices which interfere with the installation of a larger sized brake booster. Thus, the tandem type brake booster assembly (two power pistons) has been adapted to reduce the diameter of the brake booster.
This tandem type, however, has a drawback in that the entire axial length thereof must be elongated so as to arrange two pistons in tandem.